Flowers in Australia: phytochemical studies on the Illawarra flame tree and Alstonville

The first reported phytochemical studies on two species of flowers in Australia enabled the identification of six secondary metabolites from Illawarra flame tree flower (Brachychiton acerifolius) and seven secondary metabolites from the flowers of the Alstonville (Tibouchina lepidota). Pelargonidin 3-(6-coumarylglucoside)-5-(6-acetylglucoside) was found to be responsible for the red colour of B. acerifolius, whereas malvidin 3-(coumarylglucoside)-5-(acetylxyloside) was responsible for the purple colour of (T. lepidota) flowers. (2S)-4,5-Dihydroxyflavanone 7-O-β-d-glucuronide methyl ester was isolated for the first time from B. acerifolius, and its absolute configuration was determined by circular dichroism spectroscopy. Some of the traditional uses of B. acerifolius could also be correlated with the known activity of the isolated metabolites.